Pope Francis marked the 25th anniversary of a landmark compilation of Catholic teaching by saying Wednesday it should be changed to address an issue close to his heart: the death penalty.

During an anniversary ceremony at the Vatican, Francis repeated his insistence that capital punishment is "inadmissible" under any circumstance. He said the death penalty violates the Gospel and amounts to the voluntary killing of a human life, which "is always sacred in the eyes of the creator."

The Catechism of the Catholic Church, issued a quarter century ago by St. John Paul II to give Catholics an easy, go-to guide for church teaching, doesn't exclude recourse to the death penalty.

While saying its need is increasingly rare "if not practically non-existent," the Catechism says capital punishment is permissible if it's the only way to defend life against an "unjust aggressor."

The death penalty has been abolished in most of Europe and South America, but it is still in use in the United States and in several countries in Asia, Africa and the Mideast.

Francis acknowledged that in the past even the Papal States had allowed this "extreme and inhuman recourse." But he said the Holy See had erred in allowing a mentality that was "more legalistic than Christian" and now knew better.

Noting that church doctrine can develop over time, Francis said the Catechism "should find a more adequate and coherent" way to express the Gospel message about the dignity and value of every human life.

"It's necessary to repeat that no matter how serious the crime, the death penalty is inadmissible because it attacks the inviolable dignity of the person," he said.

Francis has long made prison ministry a mainstay of his vocation. On nearly every foreign trip, he has visited with inmates to offer words of solidarity and hope, and he still stays in touch with Argentine inmates he ministered to during his years as archbishop of Buenos Aires.